The plague court murders : a Sir Henry Merrivale mystery / John Dickson Carr ; introduction by Michael Dirda.

Enhanced descriptions from Syndetics:

Plague Court is old and crumbling, long neglected after its lord, hangman's assistant Louis Playge, fell victim to the black death hundreds of years before. Famously haunted by Playge's ghost, the property finally has a new owner and banishing the spirit is the first order of business. And when the medium employed with this task is found stabbed to death in a locked stone hut on the grounds, surrounded by an untouched circle of mud, the other guests at Plague Court have every reason to fear an act of supernatural violence--for who among them would be diabolical and calculating enough to orchestrate such an impossible execution?

Enter Sir Henry Merrivale, an amateur sleuth of many talents with deductive powers strong enough to unspool even the most baffling crimes. But in the creepy, atmospheric setting of Plague Court, where every indication suggests intervention from the afterlife, he encounters a seemingly-illogical murder scene unlike anything he's ever encountered before...

Reissued for the first time in thirty years, The Plague Court Murders is the first novel in the Sir Henry Merrivale series. Originally published under the name Carter Dickson, it is a masterful example of the "impossible crime" novel for which John Dickson Carr is known.